and we agreed to identify only director tim healy, a veteran fbi agent who oversees the terrorist watch list of 520,000 names. >> that could be a facilitator, it could be a bomber, could be a bomb maker, anybody. anybody connected to terrorism. >> reporter: this clearinghouse of terrorist information is used every day by tsa officers, border agents, and state, local, and federal law enforcement. >> if you're speeding, you get pulled over. they'll curry that name, and if they're encountering a known or suspected terrorist, it will pop up and say call the terrorist screening center. >> reporter: how often do these encounters say? >> we're averaging about 55 encounters with known or suspected terrorists every day. >> reporter: in most cases, the encounters do not lead to arrest but provide additional intelligence. >> location of where the guy is going, what he's doing. additional associates that the subject is hanging around. >> reporter: names are frequently added and subtracted, always in secret. healy also oversees the critical no-fly list. there are 20,000 people on the no-fly list. ab